Cascade bank selection based on ambient temperature

ABSTRACT

A system for controlling the temperature of compressed gas being transferred from one or more high-pressure storage vessels to a receiving vessel includes a plurality of high-pressure storage vessels with compressed gas therein, a conduit for receiving the compressed gas from one or more of the storage vessels and being adapted to communicate with a receiving vessel to transfer the compressed gas thereto. A plurality of flow-control devices control the flow of compressed gas from one or more of the storage vessels to the receiving vessel and a controller regulates the flow-control devices in response to the ambient temperature measured by a temperature-measuring device of the system to thereby control the temperature of the compressed gas being transferred to the receiving vessel. The method in which the system of this invention operates also constitutes a part of the present invention.

BACKGROUND OF THE INVENTION

This invention relates to a system and method for transferringcompressed gas from high-pressure storage vessels to a receiving vesseland more particularly to a system and method of controlling thetemperature of compressed gas being transferred from one or morehigh-pressure storage vessels to a receiving vessel.

Cascade filling processes that employ multiple high-pressure storagevessels to charge a lower pressure-receiving vessel are known in theprior art, as exemplified in Borck U.S. Pat. No. 6,779,568. The '568patent discloses that, for a constant filling time, the peak temperatureof the gas in the receiving tank will be lower when a lower pressurestorage vessel is used first during the cascade filling process. Thus,the '568 patent teaches controlling the order in which the storagevessels are utilized based on the difference in pressure within thosestorage banks.

The prior art also teaches that the temperature rise in a receiving tankcan be limited by adjusting the filling rate from the high-pressurestorage vessels, especially at the start of the filling process when therate of temperature increases the greatest, as exemplified in Hwang, etal. U.S. Pat. No. 5,901,748 and Togasawa, et al. U.S. Pat. No.6,598,624.

A further prior art approach for limiting or controlling the temperaturerise in a receiving tank is to utilize additional hardware, such as aheat exchanger to cool the flowing gas stream from the high-pressurestorage vessels, upstream of the receiving tank. The use of suchadditional hardware is disclosed in Sugano, et al. U.S. Pat. No.6,360,793 and Cohen, et al. U.S. Pat. No. 6,619,336.

Although the above prior art disclosures focus on the impact that thefilling process has on the receiving tank; none of those disclosurestakes into account, or even recognizes the need to take into account,the impact of ambient temperature on the compressed gas within andleaving the compressed gas storage system during the process of fillinga receiving tank. For example, at low ambient temperatures (e.g.,0° F.)the impact of isentropic expansion cooling due to the reduction inpressure within the storage system can be significant, as temperaturewithin the gas storage and delivery system can approach the minimum safeoperating limit (typically −40° F.).

Based on the limitations of the prior art approaches for storing andtransferring compressed gas from high-pressure storage vessels to alower pressure-receiving vessel a need is believed to exist for animproved system for controlling (e.g., increasing or decreasing) theamount of cooling of the compressed gas to be transferred to a receivingvessel based on ambient temperature conditions. It is to such a systemand method that the present invention relates.

BRIEF SUMMARY OF THE INVENTION

In accordance with the system and process of this invention, theoperation of a compressed gas storage and delivery system is adjustedbased on changes in ambient temperature conditions in order to minimizethe impact of isentropic expansion cooling on the storage and deliverysystem. In particular, this invention has its greatest applicability ina system where compressed gas is being transferred from a series ofhigh-pressure vessels into one or more low-pressure vessels and there isa desire to cool or warm the gas being transferred. More specifically,the invention has its most preferred applicability in the fueling ofcompressed gas vehicles, such as hydrogen or natural gas vehicles, whereit is desirable to supply the vehicles with gas within a certain rangeof ambient temperature, such as above −20° F. and below 60° F.

A system for controlling the temperature of compressed gas beingtransferred from one or more high-pressure storage vessels to areceiving vessel in accordance with this invention includes a pluralityof high-pressure storage vessels with compressed gas therein and aconduit for receiving the compressed gas from one or more of theplurality of high -pressure storage vessels and being adapted tocommunicate with a receiving vessel for transferring the compressed gasfrom said one or more of the plurality of high-pressure storage vesselsto said receiving vessel. A plurality of flow-control devices isincluded in the system for controlling the flow of compressed gas fromone or more of the storage vessels to the receiving vessel. Atemperature-measuring device is employed for measuring the ambienttemperature and a controller regulates the flow-control devices based onthe measured ambient temperature to thereby control the storage vesselvolume communicating with the receiving vessel from the one or morestorage vessels, to thereby control the temperature of the compressedgas being transferred to the receiving vessel.

In the preferred embodiment of this invention a controller regulates theflow -control devices based on the measured ambient temperature bycomparing the measured ambient temperature with a preset temperature tothereby control the storage vessel volume communicating with thereceiving vessel from one or more high-pressure storage vessels.

In accordance with this invention the parameter being controlleddirectly in response to the ambient temperature is the storage vesselvolume that is placed in flow communication with the receiving vessel tobe filled; not the mass or pressure of the gas. However, the mass andpressure of gas transferred to the receiving vessel is effected by thestorage volume placed in communication with the receiving vessel duringthe transfer or filling operation.

In accordance with the broadest aspects of this invention, differentarrangements of storage vessels can be employed to establish the desiredstorage volume in flow communication with the receiving vessel at anygiven time during the filling operation. For example, a plurality ofstorage vessels having substantially the same volume can be employed tostore the compressed gas, and different numbers of storage vessels canbe grouped together under the control of an individual flow-controldevice. Thus, when it is desired to employ the smallest storage volumeto fill the receiving vessel, the flow-control device communicating withthe smallest number of storage vessels will be operated. When it isdesired to communicate a larger storage volume with a receiving vessel,then the flow -control device that communicates a greater number of thehigh-pressure storage vessels will be opened to increase the storagevessel volume in communication with the receiving vessel to be filled.

Another approach to regulating the storage vessel volume incommunication with a receiving vessel during any desired portion of thefilling cycle is to actually employ storage vessels of different volumesand then communicate a desired storage vessel with a receiving vesselthrough actuation of a corresponding flow-control device, depending uponthe storage vessel volume that is to be communicated with the receivingvessel.

Yet another approach permitting the communication of either the same ordifferent storage vessel volumes in communication with a receivingvessel at any desired time during the filling cycle is to provide aplurality of high-pressure storage vessels, each having substantiallythe same volume, and placing each of those storage vessels incommunication with a separate flow-control device upstream of a single,common conduit in flow communication with a receiving vessel to befilled. Thus, when a single flow-control device is opened only one ofthe high-pressure storage vessels will be in communication with thereceiving vessel through the common conduit; when two flow-controldevices are opened, two of such high-pressure vessels will be in flowcommunication with the receiving vessel thereby doubling the storagevessel volume in flow communication with the receiving vessel, etc. Thislatter arrangement provides substantial versatility in the storage anddelivery system by permitting the storage vessel volumes incommunication with a receiving vessel to be varied over a wide rangeduring the filling of the receiving vessel. In particular, byselectively maintaining only one high-pressure storage vessel incommunication with the receiving vessel at any given time during thefilling cycle, the same storage vessel volume will always becommunicating with the receiving vessel throughout the entire fillingcycle. Alternatively, during different phases of the filling cycle twoor more flow-control devices can be opened to thereby communicate two ormore of the high-pressure storage vessels with the receiving vessel atany given time, thereby providing a greater storage vessel volume incommunication with the receiving vessel at any desired time in thefilling cycle.

A method for controlling the temperature of compressed gas beingtransferred from one or more high-pressure storage vessels to areceiving vessel includes the steps of providing a plurality ofhigh-pressure storage vessels including compressed gas therein;connecting the plurality of high-pressure storage vessels to a receivingvessel so that the compressed gas in one or more of the high-pressurestorage vessels can be transferred to the receiving vessel; measuringthe ambient temperature and controlling the storage vessel volume inflow communication with the receiving vessel in response to the ambienttemperature to thereby control the temperature of the compressed gasbeing transferred to the receiving vessel.

In a preferred method of this invention the step of controlling thestorage vessel volume in flow communication with the receiving vessel inresponse to the ambient temperature is provided by a controllerresponsive to the difference between the ambient temperature and apreset temperature.

In one preferred method of this invention the step of controlling thevolume of gas being transferred to the receiving vessel is carried outby controlling the number of storage vessels in communication with thereceiving vessel as gas is being transferred from the storage vessels tosaid receiving vessels.

In accordance with another aspect of this invention, the step ofcontrolling the volume of gas being transferred to the receiving vesselduring a filling cycle includes the step of changing the number ofstorage vessels in communication with the receiving vessel during thestep of transferring gas to the receiving vessel, whereby different gasstorage volumes are in flow communication with the receiving vesselduring different portions of the gas transferring operation.

In accordance with another aspect of this invention the step ofcontrolling the volume of gas being transferred to the receiving vesselis carried out by communicating only one storage vessel at a time withthe receiving vessel during the entire filling operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by way of example with reference to theaccompanying drawings, in which:

FIG. 1 is a schematic view showing a system for controlling thetemperature of compressed gas being transferred from one or morehigh-pressure storage vessels to a receiving vessel in accordance withone embodiment of this invention; and

FIG. 2 is a schematic view of a system for controlling the temperatureof compressed gas being transferred from one or more of high-pressurestorage vessels to a receiving vessel in accordance with a secondembodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a storage and delivery system for compressed gas inaccordance with one embodiment of this invention is illustrated at 10.Storage and delivery system 10 includes a storage section 12 includingplurality of compressed gas storage vessels 14, 16, 18, 20, 22 and 24.It should be understood that the number of storage vessels in thestorage and delivery system can be varied; the exact number notconstituting a limitation on the broadest aspects of this invention.

As can be seen in FIG. 1, the six (6) storage vessels are arranged inthree (3), unequal size (volume) storage banks 26,28 and 30. The storagebank 26 includes three (3) storage vessels 14,16 and 18; the secondstorage bank 28 includes storage vessels 20 and 22 and the third storagebank 30 includes the single storage vessel 24. Thus, each of the storagebanks 26, 28 and 30 has a different compressed gas storage volume.

Still referring to FIG. 1, each bank of storage vessels has its flowcontrolled by a separate flow-control device. Preferably theflow-control devices are on-off supply valves 32, 34 and 36,respectively, each operable either in a fully opened or fully closedposition. As can be seen in FIG. 1, the flow-control valve 32 controlsthe flow of compressed gas from the three storage vessels 14,16 and 18in bank 26, as a unit, and directs that flow into a supply line 38 fordelivery to a receiving tank 40. In a similar manner, the flow-controlvalve 34 controls the flow of compressed gas from the storage vessels 20and 22, which constitute the second bank 28 of storage vessels. Whenthis second valve 34 is opened, it communicates the second bank ofstorage vessels with the supply line 38 for delivery of compressed gasto the receiving tank 40. Control valve 36 controls the flow ofcompressed gas from the single storage vessel 24, which constitutes thethird bank 30. When the valve 36 is opened it directs the flow ofcompressed gas through supply line 38 to the receiving tank.

It should be understood that when each of the banks 28, 30 and 32 ofstorage vessels is placed in flow communication with receiving vessel40, the pressure in the storage vessels communicating with the receivingvessel drops as gas flows into the receiving vessel until the pressurein the storage vessels communicating with the receiving vessel equalizewith the internal pressure of the receiving vessel. At that point intime the gas flow from the bank(s) of storage vessels communicating withthe receiving vessel ends.

As can be seen in FIG. 1, the group of two storage vessels 20, 22constituting the second bank 28 has twice the gas storage volume as thesingle storage vessel 24 constituting the third bank 30, and the threestorage vessels 14,16 and 18 constituting the first bank 28 has threetimes the storage volume as the single storage vessel 24 constitutingthe third bank 30. Thus, the gas storage volume that communicates withthe receiving vessel 40 through the supply line 38 can be varied byselectively opening one or more of the flow-control valves 32, 34 and36.

Still referring to FIG. 1, a temperature measuring device 42 is providedand is in communication with programmable logic controller 44. Theprogrammable logic controller 44 operates the flow control valves 32, 34and/or 36 in a programmed sequence based upon the ambient temperaturemeasured by the temperature measuring device 42. In particular, in thepreferred embodiment of this invention the programmable logic controllerincludes a preset temperature that is compared to the measured, ambienttemperature and the relationship between these latter-two temperaturesdetermines the manner in which the programmable logic controller 44functions to open, or sequence, one or more of the control valves 32, 34and 36, as described in the following example.

Assuming that the ambient temperature measured by the device 42 isgreater than, or higher than the preset temperature in the programmablelogic controller (i.e., 10° F.), thereby establishing that the coolingof the gas should be maximized as it is being transferred to thereceiving vessel 40, the programmable controller 44 will first openvalve 36 to only communicate the storage volume of storage vessel 24with the receiving vessel 40.

The pressure in the storage vessel 24, by virtue of this vesselconstituting the smallest storage volume for delivering compressed gasto the receiving vessel 40, drops to the greatest degree possible inequalizing with the pressure in the receiving vessel, thereby deliveringthe coldest gas possible by taking maximum advantage of the heat ofexpansion cooling. Next, the programmable logic controller 44 will openthe valve 34 to communicate storage vessels 20, 22 of bank 28 with thereceiving vessel 40, and thereafter will open control valve 32 forcommunicating the three storage vessels 14,16 and 18 of bank 26 with thereceiving vessel 40, thereby delivering a lower proportion of thecompressed gas to the storage vessel 40 at warmer temperatures.

Alternatively, when the ambient temperature is less than the set pointof the programmable logic controller (when it is generally cold),cooling of the gas during the transfer operation is not desirable. Underthese conditions, the programmable logic controller 44 is programmed tofirst open valve 32 to communicate supply vessels 14,16 and 18 of bank26 with the receiving tank 40. Since the pressure in these latter threecylinders 14,16 and 18 does not drop as much as the pressure did instorage vessel 24 on a warmer day (when the ambient temperature wasgreater than the preset temperature of the programmable logiccontroller) to equalize the pressure with that in the receiving vessel,the cooling of the compressed gas due to heat of expansion is minimized.

It should be understood that the programmable logic controller 44 can beprogrammed to vary the number of valves that are opened at any giventime, as well as the order in which those valves are opened, dependingupon the desired amount of cooling of the compressed gas beingtransferred to the receiving tank 40. In particular, the storage anddelivery system 10 is designed to be capable of delivering the coldestgas possible to the receiving vessel 40 when the ambient temperaturemeasured by the device 42 is higher than a preset temperature in theprogrammable logic controller 44, and the cooling of the compressed gastransferred to the receiving tank 40 is desirably minimized when theambient temperature measured by the device 42 is less than the presettemperature in the programmable logic controller 44.

In particular, the greater the pressure drop that takes place in thesupply vessel to equalize with the pressure in the receiving vessel, thegreater the cooling affect that is obtained. The greatest pressure dropis achieved by initially delivering compressed gas to the receivingvessel 40 from the smallest available volume storage vessel (i.e., 24)in the storage section 12 of the system.

Referring to FIG. 2, a second embodiment of a storage and deliverysystem in accordance with this invention is illustrated at 100. Thisstorage and delivery system includes a storage section 102 including aplurality of storage vessels or cylinders 104,106, 108,110,112 and 114.Although the storage section 102 is illustrated as including six (6)separate storage vessels, the number of vessels can be varied inaccordance with the broadest aspects of this invention.

Still referring to FIG. 2, each of the storage vessels is controlled bya separate flow control device, in the form of an on-off supply valve104A, 106A, 108A, 110A, 112A and 114A, respectively.

Each of the conduits in which the flow-control valves are includedcommunicates downstream of those flow-control valves with a common feedline 116, and this latter feed line communicates with a supply line 118for directing the flow of compressed gas from one or more of the storagevessels 104,106,108,110,112 and 114 to a receiving tank or vessel 120.

Still referring to FIG. 2, a temperature measuring device 122 measuresthe ambient temperature in the same manner as the temperature measuringdevice 42 employed in the storage and delivery system 10. Also, thestorage and delivery system 100 includes a programmable logic controller124 including a preset temperature therein. This programmable logiccontroller 124 can be the same as the programmable logic controller 44of storage and delivery system 10.

In accordance with the operation of the storage and delivery system 100,the ambient temperature measured by the temperature measuring device 122is compared to the preset temperature in the programmable logiccontroller, and based upon that comparison, the programmable logiccontroller operates the various control valves 104A, 106A, 108A, 110A,112A, and 114A in a programmed manner to aid in controlling thetemperature of compressed gas being transferred from one or more of thehigh-pressure storage vessels, 104,106,108,110,112 and 114 to thereceiving tank or vessel 120.

For example, assuming that the ambient temperature measured by thedevice 122 is more than or higher than a preset temperature in theprogrammed logic controller 124 (10° F for example), indicating that theambient temperature is warm and that the compressed gas beingtransferred to the receiving tank or vessel 120 should be cool to itsmaximum extent, the programmable logic controller is programmed toselectively open each of the valves 104A, 106A, 108A, 110A, 112A and114A, one valve at a time. In this manner, at any specific time in thegas transferring operation only one of the storage tanks 104,106,108,110, 112 and 114 will be directing the flow of compressed gas into thereceiving tank or vessel 120 to allow the pressure, in a single tank ata time, to equalize with the pressure in the receiving tank or vessel120. In this mode of operation, the order in which the individualflow-control valves are opened is not important, but it is desirablethat only one valve at a time be opened. This provides for the greatestdegree of pressure drop in the storage vessels until pressureequalization takes place with the receiving vessel 120, therebydelivering the coldest gas possible by taking maximum advantage of heatof expansion cooling.

It should be understood that the programmable logic controller 124 canbe programmed to override the above operating sequence (or any othersequence being carried out), as desired.

However, when the ambient temperature is colder than the settemperature, generally indicating that the ambient temperature is coldand that the compressed gas being transferred from the storage section102 to the receiving tank or vessel 120 does not require significantcooling, the programmable logic controller 124 can be programmed to openmore than one control valve at a time. For example, control valves 104Aand 106A can be opened first when the temperature is less than 10° F.but more than 10° F. Another valve (for example, control valve 108A)could be opened if the temperature falls to 0° F. Ultimately, all of thevalves can be opened at the same time to minimize heat of expansioncooling at the coldest temperature, e.g., −30° F., for example.

It should be understood that the above disclosed operation of thestorage and delivery systems 10 and 100, including the sequence of theiroperation, can be varied within wide limits. The most important featurein this invention is that the system is designed to control thetemperature of compressed gas being transferred from one or more high-pressure storage vessels to a receiving vessel based upon ambienttemperature conditions.

A number of modifications can be made within the scope of thisinvention.

For example, the storage and delivery system 10, rather than employingthree separate groups of storage vessels, with each storage vesselhaving essentially the same volume, can be designed so that each of thegroups 26, 28 and 30 is replaced by a single storage vessel, with thestorage volume of each vessel differing from the storage volume in everyother vessel. For example, the bank 26 vessels 14,16 and 18 could bereplaced by a single storage vessel having a storage volumecorresponding to the total storage volume provided by the storagevessels 14,16 and 18. Likewise, the storage vessels 20 and 22,constituting the second bank 28 of storage vessels can be replaced by asingle storage vessel having a storage volume equivalent to the totalstorage volume of the vessels 20 and 22. In this embodiment the storagevessel 24 will remain, presenting the desired storage vessel volume tobe controlled by the supply valve 36.

The storage and delivery systems of this invention can be employed in awide variety of applications. In one preferred application the systemscan be employed in fueling of compressed gas vehicles such as hydrogenor natural gas vehicles, wherein it is desirable to supply the vehicleswith gas within a certain temperature, such as above −20° F. and below60° F.

Although illustrated and described herein with reference to certainspecific embodiments, the present invention is nevertheless not intendedto be limited to the details shown. Rather, various modifications may bemade in the details within the scope and range of equivalents of theclaims and without departing from the spirit of the invention.

1. A system for controlling the temperature of compressed gas beingtransferred from one or more high pressure storage vessels to areceiving vessel, said system including: A. a plurality of high pressurestorage vessels including compressed gas therein; B. a conduit forreceiving compressed gas from one or more of the plurality of highpressure storage vessels and being adapted to communicate with areceiving vessel for transferring compressed gas from said one or moreof the plurality of high pressure storage vessels to said receivingvessel; C. a plurality of flow control devices for controlling the flowof compressed gas from one or more of said storage vessels to saidreceiving vessel; D. a temperature measuring device for measuring theambient temperature; and E. a controller for regulating the flow controldevices in response to the ambient temperature measured by the measuringdevice to control the storage vessel volume communicating with thereceiving vessel from said one or more storage vessels, to therebycontrol the temperature of the compressed gas being transferred to saidreceiving vessel.
 2. The system of claim 1, wherein the controllersequentially controls separate flow control devices to selectivelycontrol the storage vessel volume communicating with the receivingvessel as compressed gas is being transferred to said receiving vessel.3. The system of claim 1, wherein at least one of said plurality of flowcontrol devices controls the flow of compressed gas from a storagevessel volume to said receiving vessel that is different from thestorage vessel volume from which compressed gas is transferred to saidreceiving vessel under the control of at least one other of saidplurality of flow control devices.
 4. The system of claim 1, whereineach of said plurality of flow control devices controls the flow ofcompressed gas to said receiving vessel from a different storage vesselvolume.
 5. The system of claim 1, wherein the plurality of high pressurestorage vessels are arranged in two or more groups of storage vessels,each group of storage vessels communicating with said receiving vesselthrough a separate flow control device.
 6. The system of claim 5,wherein the storage vessel volume of each group is different from thestorage vessel volume of every other group.
 7. The system of claim 6,wherein the volume of each of the storage vessels is approximately thesame, and the number of storage vessels in each group is different fromthe number of storage vessel in every other group.
 8. The system ofclaim 1, wherein each storage vessel communicates with the receivingvessel through a separate flow control device.
 9. The system of claim 1,wherein the flow control devices are valves.
 10. The system of claim 1,wherein said receiving vessel is a tank in a vehicle to be operated bygas transferred from said one or more high pressure storage vessels. 11.The system of claim 1, said controller including a preset temperatureand said controller regulating the flow control devices in response tothe difference between the ambient temperature and the presettemperature.
 12. A method for controlling the temperature of compressedgas being transferred from one or more high pressure storage vessels toa receiving vessel, said method including the steps of: A. providing aplurality of high pressure storage vessels including compressed gastherein; B. connecting the plurality of high pressure storage vessels toa receiving vessel so that the compressed gas in one or more of the highpressure storage vessels can be transferred to the receiving vessel; C.measuring the ambient temperature; and D. controlling the storage vesselvolume in flow communication with the receiving vessel in response tothe ambient temperature to thereby control the temperature of thecompressed gas being transferred to said receiving vessel.
 13. Themethod of claim 12, wherein the step of controlling the storage vesselvolume in flow communication with the receiving vessel is provided by acontroller responsive to the difference between the ambient temperatureand a second, preset temperature.
 14. The method of claim 12, whereinthe step of controlling the volume of gas being transferred to thereceiving vessel is carried out by controlling the number of storagevessels in communication with the receiving vessel as gas is beingtransferred from said storage vessels to said receiving vessel.
 15. Themethod of claim 14, including the step of changing the number of storagevessels in communication with the receiving vessel during the step oftransferring gas to said receiving vessel, whereby different gas storagevolumes are in flow communication with the receiving vessel duringdifferent portions of the gas transferring operation.
 16. The method ofclaim 14, including the step of controlling the volume of gas beingtransferred to the receiving vessel by communicating only one storagevessel at a time with the receiving vessel during the entire fillingoperation.